Valve gear for steam engines



1,62 2 Aprll 19,1927. J' STUMPF l 5,63

VALVE GEAR FOR STEAM ENGINES Filed Feb. 19. 1921 Patented Apr. 19, 1927.

UNITED STATES JOHANN S'JUIVLF,k ,0F BERLIN, GERMANY.

vALvE GEAR` ron. STEAM ENGINES.

Application filed February 19, 1921. Serial No. 446,504.

The invention relates to improvements in valve gear for steam engines and the method of operating same.` The object is to provide a method and means .whereby the valve actuation is the resultant of the actuations of two elements rotating at different rates of angular speed, whereby a higher valve lift is secured, and whereby the adjustment of the relative rotative positions. of said rotative elements may be utilized to vary t-he out otf.

In accordance with my copending application Serial No. 886,419, filed J une 3, 19:20, for steam engines using the movements of two rotating shafts, one rotating at double the angular speed of the crank shaft, and the other at crank shaft speed, it has been my practice to utilize the rotation of one shaft to render ineffective certain strokes of rotation of the other shaft, without in any way influencing the effective strokes.V

By the method and means comprised in the present invention the two rotating elements are so correlated and the resulting movement utilized as to secure the same high valve lift as described in the above inentioned application, and by shifting'the relative rotative position of one rotative element, withV respect to the other, the cut-ofil can be regulated as required, while the beginning of the admission is kept constant.

The advantage of such control', is the possibility of securing, with engines working only with short cut-ofi,fthe rapid valve actuation and -high lift desired for suchV shortcut-oit, or greatly increasing the possible length of cut-oli" in cases where great overload capacity is required. The former arrangement is especially adapted to power engines in dynamo plants, and particularly for unilow engines, where very regular short cut-offs are required. Y i

The latter arrangement is adapted `to engines carrying high overloads, such as automobiles, rolling millengines and engines for driving line shafts.

As convenient means for effecting the invention, I provide the rotating elements with cranks or eccentrics and mount the eccentric parts by a screw threaded engagement, so that their relative positions may be shifted for variations as to lift and advance on each other. rThis arrangement not only aves the side flanges, which render the construction difticult, but also these threaded sections, having oblique lateral faces as commonly known, causes the advantageous self- Vembodiment of the invention;

Fig. l` is a cross-section of a horizontal steam cylinder showing a valve and valve gear with double speed lay-shaft and single speed eut-out shaft.

Fig. 2 is a side elevation and a transverse diagrammatic elevation, on an enlarged scale, showing the means for driving the first lay-shaft at two to one speed, the gear train to drive the second lay-shaft at engine Speed.

F ig. 3 is a similar showing, except that the first lay-shaft is driven at engine speed and the second lay-shaft at twice engine speed.

Similar numerals refer to similar parts throughout the several views.

The rotating elements or shafts 2 and 3 are arranged parallelv with the cylinder l, and in a plane above that of the other. Shaft 2 is provided with the fixed main eccentric 4.k This eccentric is provided with a' screw threaded periphery, upon which is mountechwith normal threaded engagement, the eccentric 5. This eccentric 5 is relatively adjustable on eccentric 4, which ad-Y justment is adapted to be controlled by any form of shaft governor as at l5. The other shaft 3 is provided with an eccentric 7 rigid therewith. A twoarmed lever 8, 9, is journalled on eccentrio. Arm 8 is connected with the eccentric rod 10 of the double or lcompound eccentric 4 and 5. The other arm 9 is connected with rod 1l, which actuates the admission valve 12.

It will thus be seen that rod l1, is moved by the lever 8, 9, the fulcrum of which is the eccentric 7. The lever end 8 is actuated by the eccentric rod l0. If the lever end 8 is moved outwardly or away from shaft 2 and atvthe same time the fulcrum 7 is also moved outwardly away from the vshaft 2, there will be little or no movementof rod 11, depending upon the ratio of actuating movements caused liv the eecentries 5 and T. llt however the tnlcrum 7 is moved inwardlytoward shatt 2, when lever end 8 is moved outwardly, the movement ot the lever end t) and eonseqnently ot' the rod 1l, is the resultant of said two eeeentrie actuated movements, which resultant movement depends upon the ratio ot the extents of said two eeeentrie actuated movements. The actuating direction oft' moveniient oit each ereentrie` is the direction ot lnoveinent ol .sin-h eccentric which tends to cause the opening oi the valve.

ln the arrangement shown. tor example in lfig. 12, the shalt 2l makes one-halt revolution to one i'ull revolution oiE shalt 25 so that with each alternate rotation ot shaft 2 and eccentric Si, the valve opening eiteet ot eceeniric is eounteraeteil liv the halt rotation ot eeeentrle T; while the eccentric eoaei's with the other revolutions of eecentrie :y lioth moving in aetnating directions, which eoaetion gives valve opening movements greater than that tine to either eoeentric alone.

'lhe driving gears 1G and 17. as shown in Fig. 2 are arranged to eanse the rotation oil" sliatt 2 at twice the angular speed of the erank shaft', and the train of gears i8, 19 and i2() causes the rotation ot' shaft 3 at the same speed as that ot the crank shaft. In this event the lilits oi the valves are part-icnlarly higln a maximum ent-oil ol 35% heing possible7 that is, on a l( 'je normal cntoil' basis an overload ot the engine to about three times its ordinary working capacity. lleve the shat't governor has tour times the power, as a result ot' Vits rotating at double speed.

(ln the other hand, liv the arrangement shown in Fig. #-3, the driving gears 16 and and 11T are ot the saine diameter so that the lav-sha'lt 2 will rotate with the same velocity as the eranlt shaft and the relation of gears itl and .20 is such that the cut-out shaft 3 will malte double the number o'lf rotations. ln this` wav a maximum eut-eti' as high as 6531);: is attainable` in which event the litt is not as high as in the l'irst torim lint is still doulile that olf the ordinary regulating arrangements.so that a single heatvalve can lstill he used. lilith this arrangement the governor may run with the ordinar';7 ninnlier of revolutions, but has not the exceedinglyY high lifting power oit the first form.

What l claim is l. Valve gear for steam engines comprising two eeeentrics running at diii'erent angular speeds, and valve operating meehanisnl associated therewith, including a roi-,king lever having as its tnlorum one ot said eecentries means tor estalilishing operative relationsl'iip hetween said lever and the other eccentric, and means lor communicating movement trom said lever to the valve, the elements having such operative relationship that the eecentries will Cooperate to give one valve opening movement with each rotation olf the Cranlt shaft.y said valve opening movement being greater than that drie to either eecentric alone.

2. Valve gear tor steam engines compristwo eeeentrics running at different speeds, and valve operating meehaz vm assoeiated therewith, including a rocking lever having as its tuleruln one ot said eceentrics means for establishing operative relationship between said lever and the other eccentric, and means `tor communicating movement; trom said lever to the valve, the elements having snch operative relationship that the eeeentrics will cooperate to give one valve opening movement with each rotation ot' the crank shait, said valve opening movement being' greater than that duo to either eeeentrie alone, and a governor assoeiat'ed with one eccentric.

3. Valve. gear 'tor steam engines eoii'lprising two eecentrics, one running at crank shatt speed and the other ruiming at a multiple speed thereoit and valve operating mechanism associated therewith, including a rocking lever having as its fnlernm one ol said ect-entries means for establishing operative relationship between said lever and the other eccentric, and means for communicating movement trom said lever to the valve, the elements so related that the eeoentrics will cooperate to give one valve opening movement only with eaeh rotation olf the eranlv hatt` said valve opening movement being greater than that due to either eeeentriel alone.

In testimony that I claim the tloregoing as in v invention, I have. signed inv naine.

JOHANN STUMPF. 

